Some observations on hydatidosis in Jordan

Sero-epidemiology of Hydatidosis Among General Population of Jolfa County, Northwestern Iran Using IHA, ELISA and Western Blot (2017-2018)

BACKGROUND

Human hydatidosis is mostly a latent and neglected disease with known endemicity in Iran.

AIMS

Due to the importance of this infection in the country and its latent nature, we aimed to evaluate the serological status of hydatid cyst in northwestern Iran.

OBJECTIVES

Herein, we evaluated the serological status of hydatid cyst in urban and rural inhabitants of Jolfa county, northwestern Iran during 2017-2018.

METHODS

In total, 1296 blood samples were obtained from human individuals and the presence of anti-E. granulosus antibodies was investigated using IHA, ELISA and WB.

RESULTS

Based on results, 25 IHA positive person were detected in the examined population, however ELISA test showed 14 of 25 IHA positive patients as negative. Also, 269 IHA negative fellows were shown as negative by ELISA. WB analysis of sera from 25 IHA positive subjects revealed consistent results with the ELISA test, and the most reactive SHCF Ag was a 37 KDa protein. The age-standardized seroprevalence of hydatidosis among Jolfa's general population was 1.12% with 95%CI: 1.02-1.20. Moreover, there existed a significant association between keeping/- contact with dogs (P = 0.022) as well as vegetable consumption (P < 0.001) with ELISA positive test results.

CONCLUSION

Along with such serological evidence in this region, we highly suggest physical examination and applying imaging techniques for suspected cases in the area for a better understanding of CE.

Seroprevalence of cystic echinococcosis in a high-risk area (Al-Mafraq Governorate) in Jordan, using indirect hemagglutination test

Hydatid disease (HD) is a zoonotic disease of humans and animals which is caused by infection with the larval stages of the taeniid cestodes of the genus Echinococcus. HD is endemic in many countries of the Middle East, including Jordan. The seroprevalence rate of HD in areas of elevated risk in Jordan has not previously been investigated using indirect haemagglutination (IHA) testing. In the present study, 512 blood samples were collected from recruited outpatients from an internal medicine clinic in Al-Mafraq Governmental Hospital in Jordan. Each participant signed a consent form and completed a questionnaire. The presence of antibodies specific for E. granulosus antigens was detected using an IHA test. Statistical analysis was performed by SPSS software using the Chi-square test. In all, 4.1% of the study participants were seropositive for E. granulosus IgG antibodies. There was a significant correlation between unexplained weight loss among seropositive patients (P = 0.018). Seropositivity was significantly higher in patients who slaughtered sheep inside their houses (P = 0.023). HD seroprevalence did not correlate with gender (P = 0.433), age (P = 0.880), residency status (P = 0.938), or educational level (P = 0.808). The vast majority (75.2%) of participants reported no prior knowledge about HD, and 99.8% were not aware about the etiology of the disease.

Cystic echinococcosis in Jordan: A review of causative species, previous studies, serological and radiological diagnosis

Cystic echinococcosis (CE)/hydatidosis is a zoonotic disease which occur in human and herbivore animals as a result of infection with the larval stage of the taeniid cestode Echinococcus granulosus sensu lato (s. l.). In human, CE is a serious public health concern in many parts of the world including Jordan. The present review will cover CE causative agent: E. granulosus species/genotypes; life cycle of E. granulosus parasite, all published previous studies on CE in Jordan (humans, intermediate hosts, definitive host) as well as its diagnostic methods in human.

Cystic echinococcosis in marketed offal of sheep in Basrah, Iraq: Abattoir-based survey and a probabilistic model estimation of the direct economic losses due to hydatid cyst

Cystic echinococcosis (CE) is a highly endemic parasitic zoonosis in Iraq with substantial impacts on livestock productivity and human health. The objectives of this study were to study the abattoir-based occurrence of CE in marketed offal of sheep in Basrah province, Iraq, and to estimate, using a probabilistic modelling approach, the direct economic losses due to hydatid cysts. Based on detailed visual meat inspection, results from an active abattoir survey in this study revealed detection of hydatid cysts in 7.3% (95% CI: 5.4; 9.6) of 631 examined sheep carcasses. Post-mortem lesions of hydatid cyst were concurrently present in livers and lungs of more than half (54.3% (25/46)) of the positive sheep. Direct economic losses due to hydatid cysts in marketed offal were estimated using data from government reports, the one abattoir survey completed in this study, and expert opinions of local veterinarians and butchers. A Monte-Carlo simulation model was developed in a spreadsheet utilizing Latin Hypercube sampling to account for uncertainty in the input parameters. The model estimated that the average annual economic losses associated with hydatid cysts in the liver and lungs of sheep marketed for human consumption in Basrah to be US$72,470 (90% Confidence Interval (CI); ±11,302). The mean proportion of annual losses in meat products value (carcasses and offal) due to hydatid cysts in the liver and lungs of sheep marketed in Basrah province was estimated as 0.42% (90% CI; ±0.21). These estimates suggest that CE is responsible for considerable livestock-associated monetary losses in the south of Iraq. These findings can be used to inform different regional CE control program options in Iraq.

The seroprevalence rate and population genetic structure of human cystic echinococcosis in the Middle East: A systematic review and meta-analysis

Cystic echinococcosis (CE) represents an increasing public health concern in many parts of the world, including the Middle East. The present study is the first systematic review and meta-analysis to assess the seroprevalence rate and population genetic structure of human CE in the eastern Mediterranean region. To estimate the population genetic structure, Echinococcus sequences of the cytochrome oxidase subunit 1 (cox1) gene isolated from countries from this geographical area were retrieved from the GenBank database. An electronic search for articles from 1990 until 2015 was performed using databases PubMed, ScienceDirect, and Scopus. A total of 53 articles reporting on CE seroprevalence and genotyping data met our eligibility criteria and were included in a meta-analysis. The overall CE seroprevalence rates in the general population and in individuals at high risk of infection were estimated using the random-effect model at 7.4% (95% CI = 4.8-10.6) and 10.7% (95% CI = 7.6-14.3), respectively. Risk factors including age group (P < 0.001), dog ownership (P = 0.03), residence area (P < 0.001), and educational level (P = 0.04) showed a statistically significant association with CE seroprevalence. A pairwise fixation index (Fst), used as an estimation of gene flow, suggested a moderate level of genetic differentiation between members of the E. granulosus sensu stricto (G1-G3) complex from Iranian and Turkish metapopulations (Fst = 0.171). The finding of common haplotypes may represent an ancestral transfer of alleles among populations probably during the early stages of animal domestication. The high CE seroprevalence rates found highlight the necessity of implementing appropriate public education for preventive and control strategies, particularly in individuals at high risk of infection; furthermore, our genetic findings reveal novel molecular data concerning microevolutionary events of Echinococcus isolates among Middle East countries.

Importance of cystic echinococcosis in slaughtered herbivores from Iran

Cystic echinococcosis (CE) or hydatidosis is well-known as one of the zoonotic diseases in world-wide including Iran. Hydatidosis was considered as a disease that causes severe reduction in meat wool and milk in livestock animals which all of them indicating its importance. Thus, present study was designed to evaluated prevalence of CE in slaughtered animals from Delfan region in Lorestan province of Iran. The samples 6,885 animals were considered based on type of species in a slaughter from Lorestan province. The study performed from 3 April 2009 to 3 April 2012 and inspection carried out from 4,101 cattle, 2,150 sheep and 634 goat. The liver and lungs examined based on CE and showed the highest prevalence in cattle (25.7 %) and the lowest 3.8 % in goat, likewise, CE was more in the lung than to liver. There was significant difference between species of animals and infected organ (P < 0.001). The highest prevalence was seen in winter (32.8 % for cattle, 8.1 % for goat) while, it was 15.7 % for sheep in summer (P = 0.04). Overall these data indicate the necessity of disease control strategy for reduction of CE.

Epidemiological Investigations on Cystic Echinococcosis in North-West (Sidi Kacem Province) Morocco: Infection in Ruminants

Despite alarming statistics on cystic echinococcosis (CE) in humans and the importance of dog and ruminant populations, no epidemiological investigations have been performed on CE in Sidi Kacem Province (North-West of Morocco). A part of large research project was devoted to determine the status of CE in ruminants. This paper reports the results of the investigations carried out in the 10 abattoirs of this region, over four successive years (April 2009–March 2013). A total of 1,302 sheep, 652 head of cattle, and 136 goats were postmortem examined and hydatid cysts were collected and examined. The overall CE prevalence of infection was 42.9% in cattle, 11.0% in sheep, and 1.5% in goats. The prevalence shows significant association with age in sheep and cattle; sheep above 3 years and cattle above 5 years are highly infected (64.0% and 72.2%, resp.). Only liver and lungs are found to be infected. Molecular analyses identified G1, G2, and G3 of E. granulosus sensu stricto in liver and lung samples. Cyst fertility was significantly higher in sheep (54.9%) than in cattle (50.3%). These findings suggest that control measures should target not only sheep but also cattle.

A retrospective survey of hydatidosis based on abattoir data in Kermanshah, Iran from 2008 to 2013

A retrospective study was carried out from 2008 to 2013 to estimate the prevalence of hydatidosis in ruminants slaughtered at the Kermanshah municipal abattoir, in western Iran. A total number of 663,633 livestock (393,585 sheep, 81,080 goats and 188,968 cattle) slaughtered in the 5-year period and overall 9,524 (1.43 %) livers and 13,147 (1.98 %) lungs were condemned. The lungs were more frequently infected with hydatid cysts than the livers in all animal species. The average prevalence of hydatidosis was 2.7 % in this area. The prevalence of Echinococcus granulosus infection recorded in the present study was generally lower than those reported from other regions of Iran. Greater awareness among farmers, destruction of organs containing hydatid cysts, prevention of access of dogs to raw offals and implementation of national rabies control program could be responsible factors. The results showed a significant difference (p < 0.001) in the prevalence of hydatidosis among studied animals with higher prevalence in cattle than sheep, with the lowest prevalence recorded in goats. However the annual prevalence of liver and lung condemnations due to hydatidosis was decreased in some years, but the overall trend had a variable pattern in the prevalence of hydatidosis over the study period. Data showed a significant seasonal pattern for hydatidosis in all studied animals. Liver and lung condemnations due to hydatidosis were higher in the fall for sheep and cattle, whereas in goats were higher in summer. This could be attributed to various factors such as sources of slaughtered animals, changes in management practice and ecological factors. The current results suggest that a systematic investigation that lead to a disease control strategy is required to reduce the economic and public health consequences of hydatidosis. In addition, the present survey provides baseline data for the future monitoring of this potentially important parasitic disease in the region.

Seroepidemiology of human cystic echinococcosis in Basrah governorate

An antigen of high sensitivity and 97.5% specificity prepared from hydatid cyst fluid was used in an ELISA test for a sero-epidemiological survey in areas of Basra, Iraq. The calculated predictive values for positive and negative cases were 3.5% and 96.4% respectively.

Cystic echinococcosis in slaughtered domestic ruminants from Tunisia

A total of 10,818 domestic ruminants (3913 cattle, 2722 sheep, 3779 goats, 404 dromedaries) slaughtered in various abattoirs in Tunisia between 2003 and 2010 were examined for the presence of Echinococcus granulosus hydatid cysts. The prevalence of cystic echinococcosis (CE) was 16.42% in sheep, 8.56% in cattle, 5.94% in dromedaries and 2.88% in goats. CE prevalence increased with age according to an asymptotic model and there was evidence of variation in infection pressure depending on the region of Tunisia where the animals were slaughtered. Cattle appeared to have the highest infection pressure of the species examined. The mean intensity of hepatic cysts was higher than that of pulmonary cysts in all species. The highest mean intensity of infection with E. granulosus larvae was observed in cattle (18.14) followed by sheep (9.58), goats (2.31) and dromedaries (2.12). The abundance of infection increased in a linear fashion with age in all animal species. Cyst abundance varied with species of animal and district of Tunisia. Cysts from dromedaries were more fertile (44.44%) than those from sheep (30.25%), goats (30.32%) and cattle (0.95%). The viability of the protoscoleces from fertile cysts from cattle (78.45%) was higher than those from sheep (70.71%) and camels (69.57%). The lowest protoscolex viability was recorded for hydatid cysts from goats (20.21%). This epidemiological study confirms the importance of CE in all domestic ruminant species, particularly in sheep, throughout Tunisia and emphasizes the need to interrupt parasite transmission by preventive integrated approaches in a CE control programme.

The prevalence and fertility of hydatid cysts in buffaloes from Iran

Cystic echinococcosis caused by Echinococcus granulosus is considered to be an important parasitic infection in livestock. In the present study, which aimed to determine the epidemiology of hydatidosis in buffalo in Iran, slaughterhouses of West Azerbaijan (Urmia), East Azerbaijan (Tabriz), Ardabil (Ardabil), Gilan (Rasht and Hashtpar) and Khuzestan (Ahvaz) were inspected. Age, sex and infected organs were recorded separately, and the observed cysts were examined for fertility and viability. Our results showed that 344 (9%) of 3832 inspected buffaloes were infected with hydatid cysts. The maximum and minimum infection rates occurred in Khuzestan (9.9%) and Ardabil (8%) provinces, respectively. There was no significant difference in the rate of infection in all provinces. Of 344 infected buffaloes, the rate of fertility was 7.3% and the rate of viability in fertile cysts was 78.75%. Hydatid cysts were more prevalent in female compared with male buffaloes (P < 0.05). There was a positive correlation between the age and number of infected hosts in all provinces except East Azerbaijan. The prevalence of infection in lungs was significantly higher than that in the livers of buffaloes in the provinces studied (P < 0.001). In conclusion, the fertility of hydatid cysts in buffaloes was low, as previously demonstrated in cattle, and this animal may play a minor role in the epidemiology of hydatidosis in Iran.

An abattoir-based study on the prevalence and economic losses due to cystic echinococcosis in slaughtered herbivores in Ahwaz, south-western Iran

A 10-year (1998–2008) retrospective study was carried out to investigate the prevalence and long-term trend of hydatid disease in slaughtered herbivores in the large complex abattoir of Ahwaz (the capital of Khuzestan province, south-western Iran). A total of 3,583,417 animals including 2,815,982 sheep, 427,790 goats and 339,645 cattle were inspected macroscopically for hydatid cysts in the 10-year period, and overall 155,555 (4.24%) livers and 228,172 (6.37%) lungs were condemned. Cystic echinococcosis (CE) was responsible for 36.08% and 48.04% of total liver and lung condemnations, respectively. The prevalence of pulmonary hydatid disease in sheep, goats and cattle was 2.22, 5.43 and 6.99%, respectively; on the other hand, the prevalence of hepatic hydatid disease for those animals was 1.26, 2.57 and 2.80%, respectively. Data showed an overall downward long-term trend for CE in all livestock slaughtered during the study period (P < 0.01). Lung condemnation due to CE was significantly more common than liver condemnation for each animal separately (P < 0.001). The prevalence of liver and lung hydatidosis in sheep was significantly lower than that in other livestock (P < 0.001). The prevalence of hydatid disease recovered from the sheep, cattle and goats varied in different seasons, but there was no statistical difference between various seasons. The odds ratio of lung and liver condemnations due to hydatidosis showed a slightly different pattern in some years; however, the overall declining trend was still observed. The total annual economic loss incurred due to hydatidosis in all ruminants slaughtered at Ahwaz municipal abattoir was estimated to be US$459,659.6, based on the market prices in the year 2008. This number corresponds to a loss of US$300,620.4 for cattle, US$123,490.0 for sheep and US$35,549.2 for goats. The current results provide baseline data for the future monitoring of this potentially important disease in the region, and also suggest that a thorough investigation leading to a disease control strategy is required to reduce the economic and public health consequences of CE.

The prevalence, intensity and viability of hydatid cysts in slaughtered animals in the Ardabil province of Northwest Iran

In a cross-sectional study, a total of 5381 slaughtered animals, namely 928 cattle, 243 buffaloes, 3765 sheep and 445 goats were inspected macroscopically for hydatid cysts in northwest Iran, with prevalence values of 38.3%, 11.9%, 74.4% and 20%, respectively, being recorded. Prevalences were higher in females compared with males, but a significant difference (P < 0.001) was only found in sheep and cattle. Most cases which were condemned were seen in the lungs of sheep (13.4%) indicating that sheep are the most important intermediate hosts for Echinococcus granulosus in this area.

A retrospective survey of hydatidosis in livestock in Shiraz, Iran, based on abattoir data during 1999–2004

Meat inspection records in an abattoir located in Shiraz, a city in southwest Iran and the capital of Fars province, during a 5-year period from 20 March 1999 to 19 March 2004 were used to determine the prevalence of hydatidosis in sheep, cattle, and goats in the region. A total of 844,039 animals (cattle 131,716; sheep 577,090; goats 135,233) slaughtered in the 5-year period and overall 34,856 (4.1%) livers and 123,402 (14.62%) lungs were condemned. Hydatidosis was responsible for 28.7 and 15.4% of total livers and lungs condemnations, respectively. The overall trend for all livestock and in both organs was a significant downward one. The annual prevalence of liver condemnations due to hydatidosis was decreased from 2.1, 1.8, and 1.0% in 1999-2000 to 0.62, 0.33, and 0.20% in 2003-2004 for cattle, sheep, and goats, respectively. The corresponding features for lung condemnation due to hydatidosis were relatively higher than liver, declining from 3.0, 4.6, and 4.4% in 1999-2000 to 1.3, 1.5, and 0.56% in 2003-2004, for cattle, sheep, and goats, respectively. Greater awareness among farmers, destruction of organs containing hydatid cysts, prevention of access of dogs to raw offals and implementation of national rabies control program could be responsible factors. Data showed significant seasonal pattern for hydatidosis in all species. Liver condemnations due to hydatidosis were higher in the spring and summer for sheep, whereas lung condemnations were higher in summer for both sheep and goats. Liver and lung condemnations in cattle were higher in winter. This could be attributed to various factors such as sources of slaughtered animals, changes in management practice and ecological factors. The overall trend was relatively the same when annual condemnations were adjusted for the effect of seasonal variation. The present survey provides baseline data for the future monitoring of this potentially important parasitic disease in the region.

[Seroprevalence of infection due to Echinococcus granulosus in the population of Castilla and León (Spain)]

INTRODUCTION

Human hydatidosis is a prevalent zoonotic disease in the Castilla y León region of Spain. The aim of this study is to investigate the seroprevalence of Echinococcus granulosus infection in this region.

METHODS

We studied 4824 serum samples from a random, representative population of healthy individuals from each province of Castilla y León, obtained over one year. An indirect enzyme-immunoassay developed in our laboratory was used to determine the presence of IgG antibodies against Echinococcus granulosus in these samples.

RESULTS

IgG antibodies against Echinococcus granulosus were detected in 3.4% (164/4824) of samples studied, with a range of 1.26% to 7.10%, depending on the province. Antibody seroprevalence increased significantly with age, but there was no significant sex-related difference (3.66% men vs. 3.14% women).

CONCLUSION

The seroprevalence of Echinococcus granulosus infection in Castilla y León is still high. These data contribute to hydatidosis surveillance within the control program for this disease.

Retrospective surgical incidence and case distribution of cystic echinococcosis in Jordan between 1994 and 2000

A retrospective follow-up study on the surgical incidence of cystic echinococcosis (CE) was carried out in major governmental, military and private hospitals throughout Jordan between 1994 and 2000. A total of 472 cases were recorded over the 7-year period and an overall mean annual surgical incidence (MASI) of 2.3 per 100,000 inhabitants was estimated. The highest number of surgical cases was recorded in hospitals of the middle region of the country. The highest MASI (3.6 per 100,000) was found in the southern region while the lowest (1.4 per 100,000) was in the northern region of the country. Taking into consideration the population size and the origin of surgically confirmed cases of each region, a relative surgical index (RSI) was calculated at which the highest (RSI=3.4) was among cases originated from the southern region and the lowest (RSI=0.7) was among those originated from the middle region of Jordan. The northern region and desert areas (badia) showed comparable RSI at 1.0 and 1.1, respectively. Males younger than 15 years of age showed significantly higher surgical incidence than females of comparable age at a ratio of 1.6:1, whereas the number of female cases of different age groups over 15 years of age was consistently higher than that of males at a ratio of 1.25-2.5:1.0. The liver was the primary site of cyst development in 69.4% of the cases and the lung involvement accounted for 13.3% of the cases. Diagnosis of CE in Jordan relies mostly on imaging methods with serological techniques being rarely used for diagnosis. The frequency of CE recurrence was 27.5% of the cases, which may be attributed to the low use of chemotherapeutic antihelminthics among surgically treated cases.

The seroprevalences of cystic echinococcosis, and the associated risk factors, in rural-agricultural, bedouin and semi-bedouin communities in Jordan

An ELISA was used to determine the seroprevalence of cystic echinococcosis (CE), caused by Echinococcus granulosus, in representatives of the rural-agricultural, semi-bedouin and bedouin communities of Jordan. The knowledge, attitudes and practices (KAP) pertaining to the transmission of CE in such communities were also investigated. In the ELISA, serum samples from 2388 subjects were tested for IgG antibodies reacting with antigens in crude sheep hydatid fluid (CSHF). The rural-agricultural subjects were significantly more likely to be seropositive (11.4%) than the semi-bedouin (5.0%) or bedouin (3.7%), but male and female subjects were equally likely to be seropositive. Among the rural-agricultural and semi-bedouin subjects, those aged 11-20 years were most likely to be seropositive. Among the bedouin subjects, however, seroprevalence was highest for those aged 31-40 years. When the distribution of 59 seropositive subjects detected within 36 rural-agricultural households was investigated, 12 (33.3%) of the households were each found to have at least two seropositive members. Immunoblotting indicated that 27.1% of the seropositive rural-agricultural subjects showed immunoreactivity to at least one of the CSHF antigen-B components (of 8-12, 16 and 24 kDa). The living conditions, practices and lifestyles of the rural-agricultural, semi-bedouin and bedouin communities favour the spread of CE in Jordan and warrant an effective programme for the control of the disease.

Echinococcosis/hydatidosis in western Iran

In the present study, 115 stray dogs (56 males and 59 females, mixed breed), 86 golden jackal (Canis aureus, 42 males and 44 females), 60 red foxes (Vulpes vulpes, 33 males and 27 females), and three female wolves (Canis lupus) were examined for Echinococcus granulosus infection, as well as, 32,898 sheep, 10,691 goats, 15,779 cattle and 659 buffaloes for hydatid infection from five provinces in western Iran during 3 years (1997-2000). Meanwhile fertility rates of different types and forms of cysts isolated from infected animals and the viability of protoscolices were also determined. Results indicated that 19.1% of the dogs, 2.3% of the golden jackals and 5% of the red foxes were infected with Echinococcus granulosus. 11.1% of the sheep, 6.3% of the goats, 16.4% of the cattle and 12.4% of the buffaloes were also found to be infected with hydatid cyst. The cysts isolated from liver and lungs of the sheep show higher fertility rate than the cysts of liver and lungs of goats, cattle and buffaloes.

Modelling the prevalence of Echinococcus and Taenia species in small ruminants of different ages in northern Jordan

A base-line survey of Echinococcus granulosus, Taenia hydatigena and T ovis were undertaken in order to investigate the transmission dynamics of these parasites in northern Jordan. Intensity of E. granulosus infection, in sheep, increased with age in a linear fashion whilst the asymptotic prevalence was one. This implied that E. granulosus is in an endemic steady state with no evidence of protective immunity in the intermediate host. The mean number of cysts increased by 1.66 per year with approximately 0.320 infections per year, each infection consisting of 598 eggs to produce 5.2 cysts. The basic reproduction ratio (R0) was estimated to be 1.5-1.8. A similar pattern was suggested with E. granulosus in goats but the infection pressure appeared to be lower with only 0.128 cysts per year. Although infection in goats appeared to be endemic there was some evidence of departure from the model which might indicate that the model needs adjusting for this species. In the case of T. hydatigena the host age-intensity helminth distribution indicated that this parasite was hyperendemic in both sheep and goats, implying regulation by intermediate host immunity. Consequently, R0 was determined from asymptotic prevalence curves for T hydatigena and was calculated to be 4.0 and 3.1 in sheep and goats, respectively. The lower R0 in goats, together with the higher asymptotic age-intensity and age-prevalences, indicates that goats acquire immunity more slowly to T hydatigena in comparison to sheep. Taenia ovis was not detected in any animals.

An epidemiological survey of Echinococcus granulosus and other helminths in animal populations in northern Israel

In a survey carried out during the period May 1995 to November 1996, in communities of various ethnic groups in northern Israel, 206 dogs were examined for Echinococcus granulosus and other intestinal helminth parasites by arecoline hydrobromide purges and the coproantigen-ELISA. The arecoline test was performed close to the owners' homes, using plastic sheets secured to the ground. From 56 dogs examined in the Muslim town of Tamra, six (10.7%) were found to be infected with E. granulosus. Four of them also had a mixed infection of Taenia hydatigena and Dipylidium caninum (two dogs), and the remaining two dogs were infected with either D. caninum or Taenia pisiformis. An additional 18 dogs were infected with either T. pisiformis (eight dogs), D. Caninum (seven dogs), or T. hydatigena (three dogs). Two of these dogs harboured mixed infections whereas the remaining 32 dogs were free of helminths. In the Jewish villages, none of the 150 dogs examined were infected with E. granulosus, although 26 (17.3%) were infected with D. caninum, four (2.7%) with Ancylostoma spp. and one (0.7%) with Toxocara canis. Only one of the 22 stray dogs and none of the 15 jackals examined were infected with E. granulosus. However, 21 (95.4%) of the dogs and 12 (80%) of the jackals harboured helminth infections, including: D. caninum (16 dogs and seven jackals), Ancylostoma spp. (five jackals), T. hydatigena (three dogs), and T. canis (one dog). Approximately 18% of the dogs and 33% of the jackals showed mixed infections with two or more of the above helminths. In the abattoirs, 52 (5.9%) of the 874 sheep and 33 (5.3%) of the 616 goats from 17 herds slaughtered in the Muslim and Druze villages were found to be infected with E. granulosus, compared with a 0% infection rate observed in 93 sheep from two herds in Jewish villages.

Public health aspects of cystic echinococcosis in the Arab countries

Human cystic echinococcosis (CE) caused by larval Echinococcus granulosus is a zoonosis of major public health importance throughout the region comprising Arab North Africa and the Middle East. Prevalence rates are determined by epizootiological factors related to the size of stray dog population and its worm burden and to the infection rates in the intermediate host reservoir livestock population. Socio-economic development and socio-cultural practices are considered important determinants in the continued transmission of the disease. The reasons why CE remains a significant public health problem in the region are summarized.

Prevalence of hydatid cysts in livestock from five regions of Jordan

When the prevalences of cystic echinococcosis in indigenous sheep, goats, cattle and camels from five regions of Jordan were investigated, from March to December 1992, they were found to be 12.9%, 12.7%, 0.9% and 11%, respectively. They were substantially higher in sheep from Karak (27.6%) and in cattle from central Jordan (18.0% in Amman and 14.3% in Sahab) than in the same animals in other regions. Age-intensity data indicated that the parasite population is endemic in sheep and cattle and hyperendemic in goats. Infection rate increased steadily with age in sheep, but became constant in goats and cattle when they were about 2 years of age. The most common locations of cysts were the liver in sheep and goats and the lungs in cattle. Co-infection of the liver and lungs was common in sheep and cattle. Although the majority of the sheep, cattle and goats had 1-10 cysts, 20.4% of the sheep and 22.2% of the cattle had 11-50 and 11-30 cysts, respectively. Although 38.1% of the cysts in sheep were fertile, only 8.7% of the cattle cysts and 4.5% of the goat cysts were in this condition. The overall mean number of protoscolices/sheep cyst was 2.7 x 10(3); although the liver cysts had more protoscolices than the lung cysts (3.2 x 10(3) v. 1.9 x 10(3)/cyst), more of the lung cysts were viable (71.1% v. 62.3%). Some 0.2% of 13,436 sheep and 6.1% of 786 cattle imported live into Jordan were infected with hydatid cysts; 16.3% of the sheep cysts (61.4% viable) and 9.6% of the cattle cysts (76.1% viable) were fertile.

A retrospective study of human cystic echinococcosis in Jordan

Some 676 human cases of cystic echinococcosis (CE) were recorded from 18 major hospitals in Jordan from January 1985 to October 1993. The number and origins of the cases indicate that CE is an endemic and widespread disease in Jordan. Operations for the extraction of hydatid cysts represented 0.1% of all surgical operations carried out in the surveyed hospitals during the study period (excluding Caesarean sections). The mean annual surgical incidence of CE was estimated to be 0.5-8.2 per 100,000 population, depending on the governorate studied, with an overall mean of 2.9 per 100,000. Incidence was higher in the more rural eastern and south-western governorates than elsewhere, and more cases fell in the 21-30-year age group than in any other. Many more of the cases were female than male (443 v. 233; P < 0.001). The liver was the most common organ infected (54.5% of cases), followed by the lungs (12.1%), and multiple hydatidosis usually involved the liver.

Transmission dynamics of Echinococcus granulosus, Taenia hydatigena and Taenia ovis in sheep in Uruguay

A base-line survey was carried out on the transmission dynamics of Echinococcus granulosus, Taenia hydatigena and Taenia ovis in sheep in the Department of Florida, Uruguay. Mean life expectancy at birth of the sheep population in this Department was estimated at 3.5 and 4.8 years for male and female sheep, respectively. Both intensity and prevalence of E. granulosus infection increased with age providing no evidence that immunity was acquired in the population. This revealed that E. granulosus was only relatively stable and in an equilibrium endemic steady state with an estimate of the basic reproduction ratio (Ro) of about 1.2. The mature larval population in sheep was over-dispersed with parameter k, from fitting a negative binomial, being 0.199 and 0.556 in 42- and 54-month-old sheep, respectively. The mean number of cysts increased by 1.05 cysts per year and the infection pressure was calculated as 0.174 infections per year, implying that each infection consisted of 693.6 eggs to produce 6.03 cysts. Neither intensity nor prevalence of infection with T. hydatigena or T. ovis increased with age. This indicated that immunity was acquired to reinfection by both parasites and they were in an equilibrium hyperenedemic steady state with an estimated Ro of 4.2-5.8. Viability and fertility of E. granulosus, and viability of T. hydatigena cysts in the older age groups were low. The effects of the different transmission levels of the parasites on potential control strategies are discussed.